1. Field of the Invention
This invention relates to machine elements and mechanisms generally, but more particularly to miniaturized motors.
2. Description of the Related Art
Existing designs for canned drink vending machine motors that operate at or above 100 inch-pounds are characterized by heavy duty shaded pole motors, zinc gear boxes, all metal gears with sleeve or needle bearings, and oversized installation envelopes.
In addition, the cost and weight for such designs are among the highest for subfractional horsepower gear motors. For example, present designs for vending machines include add-on brackets for custom mounting. Moreover, it is generally known that shaded pole motors are among the most inefficient types of motors in general use. Exemplary prior art devices are discussed below.
U.S. Pat. No. 5,446,326 issued to Scheider on Aug. 29, 1995, for a vending machine gear motor including a plastic gear box. As shown in FIG. 1 of his U.S. Patent, the gear motor of Scheider comprises a gear box 11 having a generally hollow plastic gear box housing 12, a gear train 14 mounted therein, and an electronically insulating cover 13.
U.S. Pat. No. 5,256,921 issued to Pruis et al. on Oct. 26, 1993, for a gear motor with a rotary switch. The gear motor has an output shaft for driving a dispensing mechanism of a vending machine. As shown in FIGS. 2 and 3 of their U.S. Patent, the gear motor of Pruis et al. includes an electric motor 12 mounted on a printed circuit board 13 and also includes an output shaft 14 which drives a conventional gear reduction unit 16.
U.S. Pat. No. 5,404,060 issued to Nakahashi et al. on Apr. 4, 1995, for a miniature motor with a worm reduction gear. The miniature motor includes a motor section 1 which transmits torque generated from a motor shaft 3 to a worm 4, then to a helical gear 5 in a reduction gear section 2, and eventually to an output shaft 6.
U.S. Pat. No. 5,172,605 issued to Schwartz on Dec. 22, 1992, and is assigned to the same assignee as the present invention. Schwartz discloses an electric motor gearbox for a vending machine. The gearbox has four main parts: a housing, a minimotor, a printed circuit board, and an assembly of plastic gears.
Various other gearing mechanisms relating to relatively small motors of general interest are disclosed in U.S. Pat. No. 5,747,903 issued to Klingler on May 5, 1998 and in U.S. Pat. No. 5,734,210 issued to Keutz on Mar. 31, 1998.
Despite these recent developments, it remains a problem in the prior art to develop a compact miniature motor with high torque for a gearcase which makes efficient use of space in a vending machine.